I became a dad more abruptly than most. After illness and much too early deaths in my family, three pre-teen girls have come to call my home theirs. And while I was always a close part of my nieces’ young lives, I rather abruptly made the transition from the fun uncle to the (occasionally) boring dad full of rules and guidance.

I’ve spent a lifetime as an entrepreneur, starting a company in high school and spending every day of the next 30 years building, funding and mentoring many startups. I’ve enjoyed success, and failed more times than I remember.

But without a doubt the most rewarding -- and challenging -- startup of my life has been my family and the young women they are becoming. Now, many years have passed, and they will venture out into a world of their own soon.

I have no idea if they will be entrepreneurs like me and help start new businesses and organizations, or be part of startup teams. And frankly it doesn’t really matter. Those are their choices to make. But I do hope they’re learning to be entrepreneurial in their world view, because it will make them better at whatever life’s work they choose, and it will make them better people.

The characteristics I’ve seen over and again among the best entrepreneurs I have known, and the traits that I’ve seen that help startup teams succeed, have much in common. I think these lessons matter regardless of what path you take in life.

I want my kids to be intellectually curious. To be helpful, courageous and reach beyond their comfort zone. I want them to be driven, to have passion that makes them work hard and love doing so. I want them to define their own success and achieve it. I want them to enjoy and be happy with the life of their own making.

So here’s an open letter to my kids:

Most of this should ring familiar, even if we never said it as plainly. Some of these are lessons I’ve learned from watching you grow. And while these are drawn from deep experience and observation, I’m still figuring all of this out myself. I’m constantly learning my own lessons, making mistakes, and being reminded of the importance of these values.

Be kind.

Whether building a company or building a life, be motivated by cheerful service to others. It’s not just about profit -- or self-gain. Collaborate and help other people get ahead along your journey. Be empathetic, and help other people succeed. Your reputation will become your most leveragable asset, and pay dividends you will need some day.

Wander with purpose.

Your ambition is not for me to decide, but make it impactful. Chase it with zeal, convinced that it will be important and valuable, and that you will achieve it. Don’t avoid the path less taken, and don’t sweat getting lost. I’ve rarely seen an entrepreneur end up precisely where they first planned, but many of the best have wandered upon success because they hit the trail dedicated to exploring.

Be bold and confident.

That Pooh cartoon on the wall when you were young was intentional. You’re much braver, stronger and smarter than you know. Most startups fail because they don’t set out to solve hard enough problems, or create valuable enough solutions. Don’t be constrained to playing a role when you can write your own script. Be an expert. Show the world your high expectations of yourself.

Be a rule breaker (sometimes).

As your parent, I’ve spent years setting rules for you to follow. Most of them were to help you grow into a good person with habits that will help you succeed. But the best entrepreneurs push some occasional boundaries. Learn to question some of the rules when the timing is right. You won't always pick correctly, but learning which rules make you better, and which are just false constraints, will help you break out from the crowd.

Don’t let failure drag you down.

Venturing -- whether in business or in life -- involves a lot of failure. Many people can’t stand the risk of failing, and avoid ever trying. Others get bogged down in doubt and scars. Failure is just prelude, an experience from which you learn and become better, and that scar is really a badge proving you’re capable of trying again.

Ignore the critics.

There’s a lot of cynicism in the world, and many people get uncomfortable when you push the boundaries. There’s a ton of folks sitting in the stands, too limited to join you in the arena, telling you why you can’t achieve what you’ve set out to do, questioning your motives and trying to tear you down. Turn them into fuel for your passion and prove them wrong.

Find mentors.

Some people’s opinion and guidance do really matter, though. You can learn from your parents, but you also need mentors. I was lucky to grow up surrounded by some great people who cared about my future, who helped me discover the journey my life would take. Great entrepreneurs, great companies and great people all point to mentors that helped get them there. Be coachable. Seek it out.

Build a team that makes you better.

Good leaders create teams of diverse talent that support, challenge and help define each other’s success. Surround yourself with friends -- in high school and college, and throughout life -- that reflect the best of who you can be. Learn which ones you should really trust. This squad requires constant maintenance, though, so always be open to new players than can improve the team.

Pick your partner carefully.

Most great ventures aren’t founded alone, but have partners that have learned to trust and rely on each other. You can’t make it through business -- or life -- by yourself. Picking the right partner is one of the most critical choices you will ever make, and one of the hardest things to get right. There has to be real mutual respect and commitment, and the partners you pick have to make you proud.

Grit it out.

Adversity will come, sometimes as a slow, grinding headwind holding you back, and sometimes as a tornado that tears through your life and best made plans. How you respond is your choice, and what matters the most.

Great entrepreneurs -- and I think the most successful people in all walks of life -- have grit. Dogged determination to take on challenge, to be better than they were yesterday, more resilient and more valuable to the people and the world around them. Grit is optimism. Grit is motivation. Grit is patience. Grit is commitment. Grit is everything.